What will be the defining issue over the next ten years?

To mark the launch of The Hill’s second decade, we have asked members of Congress, newsmakers and commentators to tell us what they think will be the big issues that the House and Senate will need to deal with between now and 2015. Their answers appear below, as does a by-the-numbers look at the 114th Congress.

Rep. Dan Lungren (R-Calif.): “Whether or not we successfully created a homeland security strategy and a Homeland Security Department, and reorganized ourselves to where homeland security is at the same level of priority as national defense.”

Columnist Arianna Huffington: “There is no doubt that national security will continue to be the biggest issue over the next decade. The question is, how will we approach it and define it? Will we continue to spend untold billions on foreign misadventures like Iraq — or will we spend that money securing our ports, railways, borders and nuclear and chemical facilities? Will we properly fund our first responders? And will Democrats finally realize that they will never return to power unless they can figure out how to take the national-security cudgel out of the GOP’s hands?”

Rep. Marilyn Musgrave (R-Colo.): “Our relationship with South Korea, Iran and China. Those kinds of things are concerning me greatly ... over the long haul, these are threats that are only going to get worse to this nation.”

Former Michigan Gov. John Engler (R), president of the National Association of Manufacturers: “Jobs and growth. We need to reduce uncertainty and increase predictability in our tax, regulatory and judicial systems to foster job creation and economic growth. These are the keys to a bright and prosperous future for America.”

Mike Franc, The Heritage Foundation: “Two things I point to are coming to grips with the graying of the baby-boom generation and confronting the outmoded Great Society legacy. From that flows future federal … debates over Social Security and Medicare and even veterans benefits.”

Rep. Tom Lantos (D-Calif.): “Promoting freedom abroad has been a central tenet of U.S. foreign policy since the days of Woodrow Wilson, but our recently renewed commitment to this principle will place the growth of democracy at the top of foreign policy for years to come. It is incumbent upon Congress to fill in the broad outlines of the ideas that the current president has sketched out, and to ensure proper support for, and oversight of, future administrations’ efforts to shine the light of freedom in every corner of the world.”

Former Rep. Jack Quinn (R-N.Y.), president of Cassidy & Associates: “This whole question of Social Security and its solvency and what we put on the next generations to come. This is not a problem you’re going to solve in one or two years. … Congress also has to deal with the civility question and how Republicans and Democrats get along. And if that isn’t addressed, it’s going to impact how they solve this defining issue of Social Security.”

Rep. Nita Lowey (D-N.Y.): “What we do with Social Security and Medicare. With Social Security, making sure we don’t destroy it. I feel very strongly that it is a compact between workers and seniors.”

Rep. Henry Waxman (D-Calif.): “Whether we can get our economic house in order. I don’t think we can sustain the level of debt we have, and it’s going to get worse before it gets better. And I’m a liberal!”

Larry Sabato, University of Virginia’s Center for Politics: “2011 redistricting for the House and also state legislatures. Not because geography is destiny, but because just about everybody in the field plans to focus on redistricting reform. Greed is the root of all evil, but partisan redistricting is second to greed. … Tenure belongs in the ivory tower, not in the halls of Congress.”

Rep. Mike Conaway (R-Texas): “Social Security, Medicare, Medicaid. From a fiscal standpoint, those are the real issues on the horizon. They will bankrupt this country. Social Security reform will be a walk in the park compared to Medicare and Medicaid.”

Rep. Russ Carnahan (D-Mo.): “Healthcare for baby boomers, because the front end of the baby boomers are approaching retirement. That, in combination with advances in technology that we hope will transform healthcare in America.”

Republican National Committee Chairman Ken Mehlman: “The most important issue over the next 10 years will be winning the war on terror by taking the fight to the terrorists and promoting freedom abroad while simultaneously expanding opportunity at home.”

CNN’s Wolf Blitzer: “The issue of free trade and outsourcing — the whole globalization issue. That’s going to strike a huge nerve in politics over the next 10 years. As Tom Friedman calls it, ‘the world getting flatter.’”

Republican pollster Kellyanne Conway: “Spending. How we spend our money and the moral imperative that is endemic to making those tough choices. What is right and what is wrong will drive elections. Immigration is about to spike as an issue. Also, politicians will increasingly be unable to just give lip service to the issue of poverty.”

Former House Appropriations Committee Chairman Bob Livingston (R-La.): “As far as I’m concerned, it’s healthcare, especially as far as it relates to the budget. Medicare, Medicaid and to a lesser extent pensions. The impact of the baby boomers will put incredible pressures on the budget.”

Eleanor Clift, Newsweek: “The baby-boom generation has redefined every stage of life, and as the boomers move toward retirement issues surrounding medical technology and death and dying will be regularly debated. The economy is headed for a train wreck, and environmental issues will force their way onto the agenda. Twin crises of excessive debt and violent weather caused by climate change will get the country’s attention and the politicians will have to act. Terrorism will almost inevitably take a nasty turn with a suitcase nuclear bomb or some kind of biological attack.”

CongressIn 2005, there are 69 female House members and 14 female senators. In 2015, I reckon there will be 90 women in the House and 20 in the Senate.

Florida will have more than 1 million more people than New York and may gain another House seat.

California will have more than 40 million people and 54 representatives.

Arizona will have the same number of representatives as Massachusetts.

In Texas, state senators will represent larger districts than U.S. representatives. Projections are for Texas to have 35 House members, compared to 31 senators in the state Senate.

The 11 core southern states and the mountain and Pacific west states have 231 seats. In 2015, they will likely have gained 10 to 12 more seats.

The United StatesThe U.S. will have added about 25 million people up from its current nearly 290 million to neat 315 million in 2015.

The median age of Americans will have increased by more than a year from nearly 37 to nearly 38 in 2015.

The Hispanic population will have grown from 38 million to almost 50 million, from about 13 percent of the population to 16 percent.

The Asian population will have grown from 13 million to 17 million.

California will have a larger population than Poland or Canada in 2015.

Georgia and North Carolina will each have a greater population than New Jersey.

Potential shifts Illinois may trend even more Democratic in presidential contests. If Democrats continue to hold the governorship in 2010, they will be a position to redistrict heavily in their favor.

Republican-controlled redistricting could significantly alter the make up of the Georgia and North Carolina congressional delegations. Each currently has a 7 to 6 Republican majority.

Large Republican majorities in the congressional delegations of certain states may not last. Pennsylvania (12R, 7D) and Michigan (9R and 6D) have narrow Republican majorities in the state legislatures and Democratic governors. Florida (18R 7D) and Ohio (12R 6D) may see their Republican dominance of the delegation wane if they elect Democratic governors in 2010.

If California Gov. Arnold Schwarzenegger (R) passes his plan to introduce a non-partisan redistricting panel, it could impact the makeup of the delegation, although it is not clear if this favors one party or the other.

In the Senate, Republicans hold only nine senate seats in states that John Kerry won and only one Senate seat in a state he won by more than 10 percent (Lincoln Chafee of Rhode Island). Democrats hold 16 Senate seats in states that President Bush won and 11 from states he won by more than 10 percent. With retirements and tough challengers, Republican have a good shot to pick up Senate seats in these states.

Because new immigrants may not be citizens and because Hispanics are on average younger and because voting rates of new voters is low, Hispanics do not make up as large a percentage of the electorate as they do the general population. With continuing immigration, naturalization and integration, Hispanics will become a larger percentage of the electorate.

People and OfficesSen. Robert Byrd (D-W.Va.) will turn 98 in 2015, and he’ll be gearing up for his 2018 race, when he will be 101. Byrd, in 2015, has served in the Senate for 57 years, having long ago passed Strom Thurmond’s 47 years and 5 months..

In 2015, John Dingell (D-Mich.) will celebrate his 60th year in the House, long having surpassed Jamie Whitten’s record of 53 years and two months. As his father once held the same seat, it will also be the 82nd straight year that a Dingell has held the seat.

In 2015 Dennis Hastert (R-Ill.) will have served 16 years as speaker, just short of Sam Rayburn’s record of 17. Hastert passed Tip O’Neill’s record of 10 consecutive years as speaker at the start of the 109th Congress in 2009.